SCCG-Report-Part-4-C

Arup Demonstrating Climate Change Adaptation of Interconnected Water Infrastructure Contents Page Introduction 1 1.1 Case study approach 2 1.2 Selection 2 1.3 Stakeholder Workshops 3 Sydney’s CBD: Understanding the implications of sea level rise and tidal locking in an existing area of high value assets 4 2.1 Overview 4 2.2 Focus and Scope 4 2.3 Risk Assessment 10 2.4 Adaptation Options 17 2.5 Flexible Adaptation Pathway 20 2.6 Ongoing Monitoring and Evaluation 20 Green Square: New development accommodating the impact of sea level rise on the drainage network 22 3.1 Overview 22 3.2 Focus and Scope 24 3.3 Risk Assessment 26 3.4 Adaptation Options 31 3.5 Flexible Adaptation Pathway 37 3.6 Ongoing Monitoring and Evaluation 38 Cooks River: Improving governance arrangements to address existing and future flooding impacts 40 4.1 Overview 40 4.2 Focus and Scope 43 4.3 Risk Assessment 47 4.4 Adaptation Options 50 4.5 Flexible Adaptation Pathway 58 4.6 Ongoing Monitoring and Evaluation 60 Wollongong: A systems approach for interconnected coastal asset owners to adapt to coastal recession 62 5.1 Overview 62 5.2 Focus and Scope 63 5.3 Risk Assessment 65 Synthesis Report – Part 4 – Case Studies Page i Arup Demonstrating Climate Change Adaptation of Interconnected Water Infrastructure 5.4 Adaptation Options 71 5.5 Flexible Adaptation Pathway 89 5.6 Implementation 90 5.7 Ongoing Monitoring and Evaluation 91 5.8 Attachments 93 Berry Creek: Valuing community and ecological assets in the adaptation of interconnected water networks under multiple ownership 129 6.1 Overview 129 6.2 Focus and Scope 131 6.3 Risk assessment 136 6.4 Adaptation options 141 6.5 Flexible Adaptation Pathway 144 6.6 Implementation 145 6.7 Ongoing monitoring and evaluation 145 Synthesis Report – Part 4 – Case Studies Page ii Arup Demonstrating Climate Change Adaptation of Interconnected Water Infrastructure Introduction Interconnected water infrastructure is infrastructure where management is shared between agencies or different tiers of government. This can be as a result of physical interconnectedness or shared financial or asset management due to overlapping governance. Climate change will require water infrastructure managers to adapt their asset management and investment programs. This study takes a case study approach to explore this adaptation decision making process through a six stage process. The report presents a decision making framework for climate change adaptation for interconnected water infrastructure as follows: Part 1 – Overview: Provides an overview of the study, the general objectives and the issues and challenges facing interconnected water infrastructure managers in the context of climate change. It also provides a summary of key findings. Part 2 – User Guide: Provides a summary of each stage of the framework including what the stage involves, why it is important and a brief explanation as to how it is to be completed. Part 3 – The Adaptation Resource Center: The report is also accompanied by an interactive PDF (iPDF) which provides a greater level of detail as to ‘how’ each stage is to be completed including links to relevant tools. This is an interactive tool available on line at Demonstrating Climate Change Adaptation of Interconnected Water Infrastructure Part 4 – Case Studies: This section of the report provides details of how the approach was developed from and adopted on each of the five case studies and highlights lessons learnt. Synthesis Report – Part 4 – Case Studies Page 1 Arup Demonstrating Climate Change Adaptation of Interconnected Water Infrastructure Case study approach The project has identified five case studies through which climate change impacts on interconnected water infrastructure have been explored and adaptation pathways and responses assessed. The findings and case study process has lead to the development of a framework to guide decision makers with adaptation of interconnected water infrastructure. Guidance on adapting interconnected water infrastructure to climate change will be relevant to all councils and water infrastructure managers within the Sydney coastal region and beyond. However, the project deliberately adopted a case study approach to develop appropriate guidance through consideration of ‘on the ground’ in real-world scenarios. The case studies selected differ in terms of the climate problems faced as well as the governance structures and political and social context through which decision making must occur. The case studies are also in different stages in terms of the progress that has already been made in establishing adaptation pathways. The study attempts to progress each case study through a framework for adaptation decision making. However, the greater value of the case study approach is in presenting each case study’s ‘story’: City of Sydney CBD: Understanding the implications of sea level rise and tidal locking in an existing area of high value assets. Green Square: New development accommodating the impact of sea level rise on the drainage network. Cooks River: Improving governance arrangements to address existing and future flooding impacts. Wollongong: A systems approach for interconnected coastal asset owners to adapt to coastal recession. Berry Creek: Valuing community and ecological assets in the adaptation of interconnected water networks under multiple ownership. The five case study stories communicate the interconnected nature of the problem, the barriers faced, barrier resolution and consideration of long term Flexible Adaptation Pathways. In this way, the project outcomes may be more readily communicated and applied to the wider group of stakeholders. Selection The Water Research Laboratory (WRL) was commissioned by Sydney Water (SWC) to undertake a literature review, project plan, and case study selection process prior to the Sydney Coastal Councils Group (SCCG) receiving Coastal Adaptation Pathway (CAP) funding. The aim of the WRL work was to inform the case study selection criteria and provide a more detailed project plan for the project. A workshop was hosted by WRL on 24 August 2011 to discuss the progress of the literature review, and present the draft project plan and draft case study selection criteria. A report was written by WRL combining these three elements. Synthesis Report – Part 4 – Case Studies Page 2 Arup Demonstrating Climate Change Adaptation of Interconnected Water Infrastructure A call for case studies occurred in October/November 2011 inviting project stakeholders, including all SCCG member councils, to participate in the selection process. Five case studies were selected based on the following criteria: Interconnectedness. Data availability. Barriers to adaptation. Diversity of climate change impacts. Vulnerability to climate change. Stakeholder Workshops Following the selection process, and commencement of this project, an initial workshop (Workshop 1), involving delegates from asset owners, local government and industry bodies, and combining all case studies was undertaken on 28 March 2012 at which: Climate change events and consequences to be considered for each case study were selected and agreed. Potential adaptation options and barriers to adaptation were selected. A second workshop for each case study was held between Monday 23 April and Thursday 26 April 2012. The purpose of the Workshop 2 series was to: Introduce and discuss the high level ‘Flexible Adaptation Pathways Decision Making Framework’. Confirm the climate change parameters, events, impacts and adaptation options. Discuss and agree on the Flexible Adaptation Pathways for the case study. Discuss and agree on the high level economic assessment framework and the specific case study approach. Confirm the adaptation barriers and actions to overcome them. Agree on the next steps for the case study. Synthesis Report – Part 4 – Case Studies Page 3 Arup Demonstrating Climate Change Adaptation of Interconnected Water Infrastructure Sydney’s CBD: Understanding the implications of sea level rise and tidal locking in an existing area of high value assets 2.1 Overview The stormwater infrastructure for Sydney CBD is complex and consists of both original brick oviform structures and more recent concrete box culvert and pipe networks. The majority of the stormwater networks discharge into the harbour and as such are at risk from Sea Level Rise (SLR). The majority of the trunk stormwater network in the CBD is owned by SWC, with the remainder of the network being owned by City of Sydney Council (CoS). This creates numerous issues in terms of ownership and future expansion. The network is known to surcharge in large rainfall events and it is generally considered (by CoS Council drainage engineers for example) that the current capacity of the network is between a 2 and 5 year ARI standard. Any climate change impacts, due to SLR or increased storm intensity, will therefore worsen an existing problem, potentially increasing the risk of flooding at key city locations such as the Opera House and Circular Quay. Key lessons learned from the Sydney CBD Case Study The results of this case study which focussed on the Sydney CBD showed how the initial climate change variable considered can be less of an impact than imagined. A key factor for this study was to narrow the focus and scope to an individual but significant network, to make the risk assessment process manageable with the limited data available. The team adopted a very simplistic and high level approach within the risk assessment which allowed the team to quantify the risk of sea level rise on this one drainage network. The results were surprising in suggesting that the imagined problem was worse than the modelled results and highlighted the need for the iterative approach and to be prepared to return to the Focus and Scope stage to identify other assets or climate variables to consider. This demonstrates the benefits of using the climate change adaptation framework to scope the problem and then assess the risk before developing adaptation options. The case study also demonstrated that in the absence of sufficient information, simple approximations can be adopted and used effectively to assist in narrowing the focus and scope of the problem.

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